A correctly sized wheelchair is more comfortable, safer, and better for your posture than one that's too wide, too narrow, or the wrong height. Taking four simple measurements before you buy takes less than ten minutes and can save a lot of frustration later.
Why Correct Sizing Matters
A chair that's too wide forces the user to lean sideways to reach the wheels, strains the shoulders, and makes self-propelling exhausting. One that's too narrow creates pressure on the hips and thighs, which raises the risk of pressure injuries. Incorrect seat height makes transfers dangerous. Getting the measurements right is the single most important step in choosing a wheelchair.
The Four Measurements You Need
Seat Width
Measure the widest point across the hips and buttocks while seated on a firm, flat surface. Add 2 to 4 cm for clearance — that's your minimum seat width. Standard seat widths are 40 cm, 43 cm, 46 cm, and 50 cm. Choose the narrowest standard width that gives enough clearance. A narrower chair is much easier to manoeuvre through doorways.
Seat Depth
Measure from the back of the buttocks to the back of the knee (the popliteal fold). Subtract 2 to 4 cm from this measurement. This stops the seat from pressing into the back of the knees, which would cut off circulation. Most standard wheelchairs have a seat depth of 40 to 45 cm.
Seat Height (Floor to Seat)
Measure from the floor to the underside of the knee (popliteal height). This gives you the right seat height so the feet rest flat on the footrests without the thighs being pushed up or the knees dropping below hip level. Standard seat heights are 46 to 50 cm. Adjustable footrests can compensate for small variations.
Back Height
Measure from the seat to the bottom of the shoulder blades, or higher if head support is needed. For most everyday manual wheelchairs, a back height that sits just below the shoulder blades gives good support while allowing free arm movement for self-propelling. For users who need more postural support, a higher back or headrest is the right choice.
Taking the Measurements: Step by Step
You'll need: a flexible tape measure, a firm flat chair (not a couch), and someone to help.
- Have the person sit upright on a firm chair with feet flat on the floor and thighs parallel to the ground
- Measure hip width at the widest point, add 3 cm, and record as seat width
- Measure from the back of the buttock to just behind the knee, subtract 3 cm, and record as seat depth
- Measure from the floor to the back of the knee and record as seat height
- Measure from the seat surface to the bottom of the shoulder blades and record as back height
| Measurement | How to take it | Adjustment |
|---|---|---|
| Seat width | Widest hip/buttock point seated | Add 2 to 4 cm |
| Seat depth | Back of buttock to behind knee | Subtract 2 to 4 cm |
| Seat height | Floor to underside of knee | No adjustment needed |
| Back height | Seat to bottom of shoulder blades | Higher if head support needed |
Key takeaways:
- Four measurements are needed: seat width, seat depth, seat height, and back height
- Always measure seated on a firm, flat surface with correct posture
- Add clearance to width; subtract from depth to avoid pressure behind the knees
- If you're not sure, an occupational therapist can take the measurements and make recommendations for you
Browse our wheelchair range once you've got your measurements. Our guide on buying a wheelchair for an elderly parent also covers what else to consider before you buy.